microbio unit 4 microorganisms causing infection

the human host

the human body is in equilibrium with microorganisms but sometimes the balance becomes in favor of the microbes and thats when disease results

factors that weaken the hosts defences

old age

surgery

underlying health conditions

cancer

liver malfunction

immuno suppressive drugs

other infections

cause of disease in the body

1. microorganisms

2. malfunctioning of organism diabetes

3. nutritional deficentcy rickets

4. allergic reaction asthma

5. abnormal growth of cells cancer

pathogen

microbe whose relationship with the human host is paracitic and results in infection/ disease

disease

deviatiion from health

infectous disease

disruption of a tissue or organ caused by microbes and their products. when microorganisms multiply and cause damage to tissues. could either be exogenous or endogenous

pathogenicity

severity of infection depends on the pathogenicity of the organism and the condition of the host

what does endogenous and exogenous refer to

the sources of microorganisms

endogenous infectious disease

MO naturally occuring in the body.

does not cause harm or overgrowth

ex. dental caries, pulpitis, periodontal disease, actinomycosis

exogenous infectous disease

MO not normally present in the body but contaminates the body from the outside

ex. hep b , strep throat, aids, chicken pox, common cold, flu

exogenous disease development

1. scope of microorganisms

2. escape of MO from the source.

3. spread of MO to a new person

4. entry of MO to a new person

5. infection (survival & growth of MO

6. damage to the body

chain of infection

1. resivour

2. portal of exit

3. mode of spread

4. portal of entry

5. suseptible host

6. pathogenic agent

1. resivour

saliva

water

feces

environement

animals

insects

stay healthy sterilization, disinfection, water asepsis

2. portal of exit

secretions, excretions, droplets, aerosols.

a high # of microbes indicate that it will most likely reach other hosts

ususally the same as portant of entry but some MO use a differnt rout

3. mode of spread

direct contact,

droplets

indirect contact

airborne

4. portal of entry

inhilation

imgestion

mucus membranes

broken skin

5. suseptible host

person at risk

6. pathogenic agent

virus

fungus

bacteria

protazoa

living resivours

animals, mamels, birds, repties

humans

arthopods:biological vectors

non living resivours

soil, water ,air, the built environment

how to spread respiratory disease

coughing, sneezing, talking

modes of transmission

1. direct contact w source

2. indirect contact

3. droplet infection from spatter splashes

4. airborne infection

1st stage of infectous disease: incubation

initial entrance of the infectous agent into the body

2nd stage of infectous disease: prodromal

appearence of early symptoms

3rd stage of infectous disease: acute

period of invasion where symptoms of the disease are maximal and person is ill

4th stage of infectous disease: convalescent

recovery phase, pathogens may spread to others during any stage

infection types: localized

microbes remain confined in a specific tissue

infection types: systemic

spreads to different sites and tissue fluids

infection types: focal

spread from local site to other tissues

infection types: mixed

several agents establish themselves in at the infection site ex human bite infection , wound infection

infection types:

infection types: secondary

second infection caused by a different microbe

infection types: acute

comes rapidly w/ severe but short effects ex. influenza

infection types: chronic

progresses and persists

pathogenicity

an organisms potential to cause infection or disease

true pathogens

capable of causing disease and infection w normal immune defences

associated with specific and recognizable disease

it varies in severity from mild to severe

examples include influenza

oppertunistic pathogens

when host defenses become compromised and the established themselves and a part of the body which is not natural to them

they don't possess well developed virulence properties

It is not consideredPathogenic to a healthy client

For example pseudoMembranous Canada albicans

pathogenic properties of MO

1. inhance infection

2. interfers with host

Bacterial toxins: endotoxin

Gram-negative bacteria contain endotoxin that when released affects phagocytes and blood platelets and can induce inflammatory response Causes shock, fever, inflammation, hemorrhage, and diarrhea

Bacterial toxins: exotoxin

• Other bacteria may produce _____ that interfere with cell or body functions such as food poisoning & tetnus

• Toxin (usually protein) is secreted and acts upon a specific cellular target 

• Example – Hemolysins, which damage and/or rupture (lysis) red blood cells 

Necrosis

• ccumulated damage due to pathogens leading to cell and tissue death

Enhancement of Infection 

• Microbes eventually settle in a particular target organ and cause damage at the site

  • Host tissues are weakened as a result of the multiplication of the pathogen

Sign

• Objective evidence of disease as noted by an observer eg. Edema

Symptom

• Subjective evidence of disease as sensed by the client

    eg. Pain 

Syndrome

• A disease identified by a certain complex of signs and symptoms (eg. Metabolic syndrome – high blood pressure, blood sugar and cholesterol)

Communicable

• A disease in which an infected host can transmit the infectious agent to another host and establish infection in that host

• Infectious is synonymous with communicable

contagous

• A disease that is highly communicable, especially through direct contact

  • Influenza and measles are highly contagious

  • Hansen’s disease (leprosy) is only weakly communicable

Noncommunicable 

• An infectious disease which does not arise through transmission of the infectious agent from host to host

  • Compromised person is invaded by their own microbiota

  • Infected persons do not become a source of disease to others

Healthcare-Associated Infections

• Infections acquired or developed during a hospital stay

Factors tied to healthcare-associated infections

• Compromised patients

• Collection point for pathogens

• Lowered defenses permit normal biota to enter the body

• Infections acquired directly or indirectly from fomites (objects or materials likely carrying infection, such as clothes, utensils, and furniture), medical equipment, other patients, medical personnel, visitors, air, and water

Control of healthcare-associated infections

• Nurses/RDH /caregivers are regularly exposed to needlesticks, infectious secretions, blood, and physical contact with patients; they need to be especially aware of infection control